Determination of Heavy Metal Contamination in Soil and Accumulation in Cassava (Manihot Esculenta) in Automobile Waste Dumpsite at Ohiya Mechanic Village

Abstract

Human health challenges resulting from consumption of food contaminated by heavy metals necessitated the investigation of soil and cassava plants around automobile waste dumpsite at Ohiya mechanic village, Abia State, Nigeria. Soil and cassava samples collected randomly at the site were analyzed for cadmium (Cd), copper (Cu), lead (Pb) and chromium (Cr). The values of highest concentration of Cu and Pb in soil was recorded in 0-10 cm, Cr was obtained in 21-30 cm while Cd was in 11-20 cm soil depth. The concentration of Cd (0.11±0.00 to 0.26±0.00 mg/kg) in soil exceed maximum permitted level of 0.1 mg/kg (Cd) by FAO/WHO. The concentration of Pb (0.01±0.001 to 3.24±0.00 mg/kg) and Cd (0.07±0.00 to 2.08±0.00 mg/kg) in cassava plants exceed the permissible limit of 0.3 mg/kg (Pb) and 0.2 mg/kg (Cd) set by FAO/WHO. The Pearson correlation analysis show very strong positive relationship between Cu and Cu (r=0.996) and Pb and Pb (r=0.986) while strong negative relationship exist between Cr and Cr (r= -0.686) and Cd and Cd (r= -0.981) in soil and plant. Based on our findings, the concentrations of Cd in soil vis-à-vis Pb and Cd in plants which exceed maximum permitted level set by Codex Alimentarius Commission FAO/WHO will expose man and animals that relied on soil and cassava plants for food to serious health risks. Consequently, Abia State government should prevent farmers’ access to the site by fencing round the automobile waste dumpsite.

Analysis of Soil Quality Status and Accumulation of Potentially Toxic Element in Food Crops Growing at Fecal Sludge Dumpsite in Ubakala, Nigeria

“…The concentrations of Cr and Pb in soil at the fecal sludge dumpsite were 2.40±0.40 to 21.03±1.43 and 0.09±0.02 to 0.35±0.03 mg/kg, respectively. The values of Cr (2.40±0.40 to 21.03±1.43 mg/kg) is well below the accepted limit of 100 mg/kg (Cr) as described by Dutch criteria for soil (Ogbonna et al, 2020a), the 100 mg/kg (Cr) established by Codex Alimentarius Commission (FAO/WHO, 2001), the 100 mg/kg (Cr) set by National Environmental Standards and Regulations Enforcement Agency, NESREA of Nigeria (NESREA, 2011), 50 mg/kg (Cr) set by Ministry of Agriculture, Fisheries and Food, MAFF (MAFF, 1992) and 50 mg/kg (Cr) set by the European Commission, EC (EC, 1986). The concentration of Cr (21.03±1.43 mg/kg) at 1 m is 2.09, 3.51, 8.76 and 2,103 times higher than its values at 5 m, 15 m, 30 m from the fecal sludge dumpsite and control, respectively.…”

“…The concentration of Pb in soil at the fecal sludge dumpsite was 0.09±0.02 to 0.35±0.03 mg/kg, which is well below 164 mg/kg (Pb) set by National Environmental Standards and Regulations Enforcement Agency, NESREA (NESREA, 2011) of Nigeria, the accepted limit of 85 mg/kg (Pb) described by Dutch criteria for soil (Ogbonna et al, 2020a) and the maximum permitted level of 50 mg/kg (Pb) established by Codex Alimentarius Commission (FAO/WHO, 2001) (Table 6). The concentration of Pb (0.35±0.03 mg/kg) at 1 m is 1.25, 2.19, 3.89 and 35 times higher than its values at 5 m, 15 m, 30 m from the fecal sludge dumpsite and control, respectively.…”

“…Source: Ogbonna et al (2020a) The surface elevation is about 120 m and the area has low-lying to moderately high plain topography. It is drained by Imo River and its tributaries are perennial, resulting in secondary rainforest vegetation along the river banks.…”

“…In furtherance of this, some proportion of the fecal sludge may contain heavy metals which is of great concern in the world. The accumulation of dissolved heavy metals in water is hazardous to water bodies and human health when their values are higher than the corresponding threshold (Pape et al, 2012;Varol et al, 2013;Bu et al, 2015;Ogbonna et al, 2020a).…”

“…Plants growing on potentially toxic element (PTE) contaminated soil tend to absorb PTE such as heavy metals from soil solution via the roots and translocate it to the stems and the leaves (Ogbonna et al, 2018a;2020a). The chemical form of potentially toxic element in soil can strongly influence their uptake by plants as mobile ions present in the soil solution through the roots resulting in bioaccumulation of the elements in plants tissues (Pitchell and Anderson, 1997;Davies, 1983;Amusan et al, 2005).…”